Building a 3D Cube

[Rochdi]

Hello Experts,

After I merged S and L cubes into a single layer, I would like to represent these spectrums (Visible, NIR and SWIR)  into a three dimensional cube. I used a "3D cube" tool in ENVI toolbox to do this, then I chose 3 bands from each mentioned spectrum to make a color composite.However, I didn't get the expected result as seen below. 

Is something wrong?
I look forward to your reply.

Rochdi.

[Ray Arvidson]

Hi: I am here to help. Tell me what you mean by a 3D cube? Do you want a data cube where planes are images and each pixel has a spectrum associated with it? So when you display the S and L combined cube and use the spectral plot as you move around the image in the display the spectrum for that location shows in a plot window. Is that what you want?  Build 3D cube does not do that and only produces a nice perspective view of the cube with an image on the top and color-coded spectral values down the side.   https://www.l3harrisgeospatial.com/docs/ImageCubes.html

Ray Arvidson  

Ah, I see the problem with 3D data cube. It has to be a rectangular cube, square or rectangular. Not a map projected version, see attached.

Edited November 9, 2020 by Ray Arvidson
added some text

[Rochdi]

Hi Sir,

Thanks a lot for your help,

What I meant by building a 3D cube is exactly what you attached above, a 3D view of the cube with an image on the top and color-coded spectral values as well on the side.
Depending on my system capability, it seems fine to build a 3D cube only for the VNIR range.
Is it possible to build a 3D cube only for VNIR range relying on the instructions you mentioned in the link above?

I followed the instructions in your mentioned link to come up with a 3D cube for VNIR range.
I selected the input file  and I performed a spectral subsetting of 107 bands. Then, I chose the bands I want to place on the face of the image cube (R: Band 51 | G: 34 | B: 24) and a Rainbow as color side. To apply a multiplier to the pixel dimensions of the side and top, I kept the border and spectral scale values as default.

However, I come up with these unexpected output results as I attached below.

Look forward to your reply,

Rochdi.

 

Edited November 10, 2020 by Rochdi

[Ray Arvidson]

I suggest you look at the range of values in your cube. If there are extremely high excursions because of noise, or in L data, use of 65535 to indicate non-data, the system will scale its output relative to the extreme values and results will be black. Remove these values before proceeding.

Ray

[Rochdi]

Hello Sir Ray,

I did a quick stats for the VNIR range (S cube) to check which bands contain the mentioned value, and I found the first five bands of this range with 65535 value. Then, I exclude these none-data using ROI and subset to come up with a sub image without 65535 value before building the 3D cube.
Here's the outputs I came up with as I attached below (then, I edit the header file of the output by adding data ignore value = 0 in order to remove the black area that surround the cube).

Would you please let me know whether the output is accurate or not?

Rochdi.

[Ray Arvidson]

Yes, your results are what they should be, so congratulations.

Ray Arvidson

[Rochdi]

My thanks and appreciation to your help Sir Ray Arvidson .